Interpreting blood test results

[Granolalover690]

hi

this is my first time posting, I have been recently diagnosed with under active thyroid

I’ve been taking levothyroxine for about two months now

I did an at home blood test recently just to check my levels

The results were:

t4- 25.7 (11.9-21.6)

TSH- 3.09 (0.4-4.5)

t3- 4.41 (3.1-6.8)

I had taken my levothyroxine about an hour or two before my blood test- could this be why my t4 was high but the others were in normal ranges?

I have read on here since that I should’ve not taken my medication before, I will not do this next time

thank you

[SlowDragon Administrator]

Correct

ALWAYS test early morning, ideally just before 9am, only drink water between waking and test and last dose levothyroxine 24 hours before test

This gives highest TSH, lowest FT4 and most consistent results. (Patient to patient tip)

With TSH over 2 you will be needing next 25mcg increase in dose

How much levothyroxine are you taking

Which brand is it

For full Thyroid evaluation you need TSH, FT4 and FT3 tested

Also both TPO and TG thyroid antibodies tested at least once to see if your hypothyroidism is autoimmune

Very important to test vitamin D, folate, ferritin and B12 at least once year minimum

Low vitamin levels are extremely common when hypothyroid, especially with autoimmune thyroid disease

About 90% of primary hypothyroidism is autoimmune thyroid disease, usually diagnosed by high TPO and/or high TG thyroid antibodies

Autoimmune thyroid disease with goitre is Hashimoto’s

Autoimmune thyroid disease without goitre is Ord’s thyroiditis.

Both are autoimmune and generally called Hashimoto’s.

Significant minority of Hashimoto’s patients only have high TG antibodies (thyroglobulin)

NHS only tests TG antibodies if TPO are high

20% of autoimmune thyroid patients never have high thyroid antibodies and ultrasound scan of thyroid can get diagnosis

In U.K. medics hardly ever refer to autoimmune thyroid disease as Hashimoto’s (or Ord’s thyroiditis)

Essential to test vitamin D, folate, ferritin and B12

Lower vitamin levels more common as we get older

For good conversion of Ft4 (levothyroxine) to Ft3 (active hormone) we must maintain GOOD vitamin levels

What vitamin supplements are you taking

[Granolalover690 in reply to SlowDragon]

Thank you

Those results were from 4 weeks into treatment could it be that my tsh hadn’t levelled out yet or do you still think an increase might be required ?

Thanks

[SlowDragon Administrator in reply to Granolalover690]

How much levothyroxine are you taking

Standard STARTER dose is 50mcg

Typically dose is slowly increased upwards in 25mcg steps until eventually on, or somewhere near full replacement dose (typically 1.6mcg levothyroxine per kilo of your weight per day)

cks.nice.org.uk/topics/hypo...

bnf.nice.org.uk/drugs/levot...

nhs.uk/medicines/levothyrox...

Adults usually start with a dose between 50 micrograms and 100 micrograms taken once a day. This may be increased gradually over a few weeks to between 100 micrograms and 200 micrograms taken once a day.

Some people need a bit less than guidelines, some a bit more

TSH should always be below 2 on levothyroxine

gponline.com/endocrinology-...

Graph showing median TSH in healthy population is 1-1.5

web.archive.org/web/2004060...

Comprehensive list of references for needing LOW TSH on levothyroxine

healthunlocked.com/thyroidu....

onlinelibrary.wiley.com/doi...

If symptoms of hypothyroidism persist despite normalisation of TSH, the dose of levothyroxine can be titrated further to place the TSH in the lower part of the reference range or even slightly below (i.e., TSH: 0.1–2.0 mU/L), but avoiding TSH < 0.1 mU/L. Use of alternate day dosing of different levothyroxine strengths may be needed to achieve this (e.g., 100 mcg for 4 days; 125 mcg for 3 days weekly).

sciencedirect.com/science/a...

The optimal daily dose in overt hypothyroidism is 1·5–1·8 μg per kg of bodyweight, rounded to the nearest 25 μg.

Retest 6-8 weeks after each dose increase

[Granolalover690 in reply to SlowDragon]

Hi I’m on 100mcg

[SlowDragon Administrator in reply to Granolalover690]

So you started on 100mcg ?

Suggest you retest again in another 8 weeks

Then review

[Granolalover690 in reply to SlowDragon]

Yes I did, so you don’t think I need any increase now? I have a blood test booked for two weeks

[SlowDragon Administrator in reply to Granolalover690]

is that a GP test

I would perhaps delay it to 4-6 weeks from now

Always book test ideally just before 9am, only drink water between waking and test and last dose levothyroxine 24 hours before test

get vitamin levels tested via GP or privately

[Granolalover690 in reply to SlowDragon]

thank you for your advice too